Centrifugal clutch

ABSTRACT

A CENTRIFUGAL CLUTCH HAVING DRIVE AND DRIVEN MEMBERS, THE FORMER INCLUDING A DISC AND HUB, A PAIR OF WEIGHTS WITH ARCUATE OUTER SURFACES PIVOTALLY MOUNTED AT THEIR ADJACENT ONE ENDS UPON SAID DISC AND CONSTRAINED TO RADIAL MOVEMENTS, A SPRING INTERCONNECTING THEIR ADJACENT OTHER ENDS IN TENSION MAINTAINING THE WEIGHTS IN A RADIAL INWARD &#34;RELEASE&#34; POSITION, THE DRIVEN MEMBER INCLUDING A DRUM OVERLYING AND SPACED FROM THE DISC AND WEIGHTS AND HAVING A HUB JOURNALLED ON THE DISC HUB, AND A SLEEVE OF FRICTION MATERIAL MOUNTED UPON AND AROUND THE INTERIOR OF SAID DRUM NORMALLY SPACED FROM THE WEIGHTS, A MODIFIED CLUTCH WHEREIN THE WEIGHT PIVOTS ARE DIAMETRICALLY OPPOSED, AND SPRINGS INTERCONNECT THE RESPECT OPPOSITE ENDS OF THE WEIGHTS, AND A FURTHER MODIFICATION WHEREIN THE WEIGHTSD ARE CONSTRAINED TO RADIAL MOVEMENTS.

W. H. DE LANCEY CENTRIFUGAL CLUTCH Jan. 5, 1971 Filed Sept. 24, 1968 3Sheets-Sheet 1 WARR 11 g? NLTAOR 5v I v e BY 6 %n%, a? g wfz ATTORN EYSJan. 5, 1971 w. H. DE LANCEY CENTRIFUGAL CLUTCH 3 Sheets-Sheet 3 FiledSept. 24, 1968 INVENTOR WARREN H. De LANCEY ATTO R N EYS United StatesPatent US. Cl. 192105 4 Claims ABSTRACT OF THE DISCLOSURE A centrifugalclutch having drive and driven members, the former including a disc andhub, a pair of weights with arcuate outer surfaces pivotally mounted attheir adjacent one ends upon said disc and constrained to radialmovements, a spring interconnecting their adjacent other ends in tensionmaintaining the weights in a radial inward release position, the drivenmember including a drum overlying and spaced from the disc and weightsand having a hub journalled on the disc hub, and a sleeve of frictionmaterial mounted upon and around the interior of said drum normallyspaced from the weights; a modified clutch wherein the weight pivots arediametrically opposed, and springs interconnect the respect oppositeends of the weights; and a further modification wherein the weights areconstrained to radial movements.

While centrifugal clutches are useful, and desirable in manyapplications, their use has been retarded by high manufacturing cost. Itis an object of the present invention to simplify the construction andmake it of materials which can be fabricated rapidly in high productionwith a minimum of subsequent operations.

It is the usual purpose of a centrifugal clutch to connect a rotatingshaft to a driven load after a predetermined speed has been reached, andto disconnect that load in case the speed of the rotating shaft dropsbelow a specified r.p.m. Thus the power source is only connected to theload after it has attained a predetermined speed. As in the case ofinternal combustion engines, and certain types of electric motors, thetorque at low rotating speeds, is minimal, and it is desirable that thepower source be disconnected when starting, or if it falls below a givenr.p.m., in order to prevent stalling. There are many other applications,for instance, on automatic washers, where a single motor may beconnected to several loads, one of them with relatively low torquerequirements, and another with high torque requirements. If the latteris connected through a centrifugal clutch, it permits the use of a lessexpensive motor with lower starting torque availability. Low startingtorques permit the use of shaded pole or permanent split capacitormotors, and these make possible motor speed control through voltagechange, wave clipping, or frequency modulation. Motor speed change,coupled with a centrifugal clutch, permits automatic control of loadconnection, often eliminating an extra motor which would otherwise haveto be used.

There are, in general, two type of loads to be coupled to a powersource, low inertia and high inertia. A good example of a low inertiaload is a hydraulic pump where the gears or impellors usually haverelatively low mass. A good example of a high inertia load is a largeSirrocco type blower wheel which has a relatively high mass. The

"ice.

low inertia loads can be accelerated very rapidly with a self-energizingtype of clutch which grabs and holds, but high inertia loads are bestaccelerated gradually to avoid high stresses on the driving parts, whichrequire a clutch capable of picking up the load gradually.

These and other objects will be seen from the following specificationand claims in conjunction with the appended drawing in which:

FIG. 1 is a fragmentary partially sectioned view taken in the directionof arrows 11 of FIG. 2.

FIG. 2 is a longitudinal section of the present centrifugal clutch takenin the direction of arrows 22 of FIG. 1.

FIG. 3 is a right side elevational view thereof.

FIG. 4 is similar to FIG. 2 showing a modification.

FIG. 5 is an end elevational view thereof, with a removable flexiblecoupling member shown in cross section.

FIG. 6 corresponds to FIG. 1 showing a modification thereof.

FIG. 7 is a fragmentary section taken in the direction of arrow 77 ofFIG. 1.

FIG. 8 is a view corresponding to FIG. 1 illustrating a modified clutch.

FIG. 9 is a similar view showing another modification.

FIG. 10 is a fragmentary section taken in the direction of arrows 1010of FIG. 9.

Referring to the drawin s FIGS. 1, 2 and 3 illustrate one form ofself-energizing centrifugal clutch generally designated at 10 (FIG. 2)and including drive member 11 and driven member 12. Said drive memberincludes a disc 13 which is centrally apertured and projecting from oneside of the hub 14 which has central bore 15 terminating in counter bore16, the latter being suitably splined or provided with a flat as at 17(FIG. 3) adapted to receive a prime mover such as a power-driven shaft.The hub may be restrained from linear movement by the use of aconventional radial set screw or a fastener upon the end of the driveshaft, not shown.

A pair of pivot hubs 18 form a part of and project at right angles fromdisc 13, as in FIG. 1. A pair of symmetrical oppositely arranged weights19 are apertured at their one ends and mounted upon hubs 18 adjacentdisc 13 (FIG. 2). The outer working surfaces of the weights are arcuateas at 20 and there is provided a normal working surface A-B which isremote from pivot 18 normally adapted for uniform frictional registrywith a friction surface 38 hereafter described. Said arcuate surfacesare so shaped that these surfaces as at A-B will be substantiallyuniform in curvature for registry with the friction material 38. Thiscontact A-B will occur at the maximum distance from pivot 18 and is suchthat depending upon the direction of rotation of the drive member 11 oneof the weights 19 has a distinct tendancy to be rotated about its pivot18 and forced into harder contact pressure with the friction member 38,whereas the other weight has the opposite effect. The former tendancy isreferred to as self-energizing.

Thus the weights 19 shown in FIG. 1 provide a clutch which isself-energizing regardless of the direction of rotation of the drivemember 11.

The outer end of each weight remote from its pivot on one side thereofhas an arcuate slot 21 therein which extends approximately midway of itswidth to define an arcuate post 22. As for example, the upper weightshown in FIG. 1 with the post for illustration extending toward thereader. The corresponding opposing weight 19 is of the sameconstruction, but is positioned so that its arcuate recess is upon theopposite side so that the post defined at 22 extends in the oppositedirection. Thus the two posts 22 are adapted for connection to theopposite looped ends of the coil tension spring 23 for normally holdingthe weights in the inoperative or release position shown. In thisposition the respective weights bear against the corresponding flatsurface 25 of the semi-cylindrical stop posts 24 which project from disc13.

Circular lip 26 upon the outer end of the said post 24 registers with acorresponding arcuate recess 27 formed in the respective weights inorder to guidably receive said weights and to limit their motion toradial movements within the confines of drum 28.

The stops 24 are supported at the hub 14 and are integral with it forapproximately one-half of their length to thus provide a solid stop andto prevent stresses on the disc 13 through cantilever action.

The driven member '12 of the centrifugal clutch includes a cylindricaldrum 28 (FIG. 2) which is closed by a substantially angular but radialweb 29 at one end and is open at 30 at its other end (FIG. 2). The drum28 includes axial hub 31 which projects from one side of web 29, and ahub extension 32 extending from its opposite side and whichcooperatively nests within an annular slot 33 formed within hub 14adjacent the posts 24.

In the assembly shown in FIG. 2 this construction limits relativeendwise movements between drive member 11 and driven member 12 in onedirection. Hub 14 includes a reduced extension 34 over which is mountedwasher 35 retained in position by the turned over end portion 36 (FIG.2), said washer serving to restrain the members 11 and 12 againstrelative longitudinal movement in the opposite direction.

Drum 28 within its cylindrical portion includes the bore 37 upon whichis mounted a suitable friction sleeve 38 employing a suitable adhesiveas desired and which could be of any epoxy or other resin or othersuitable adhesive. The material of the sleeve 38 may be of bonded corkfor low inertia loads where there is little slippage in the clutch, ormade of bonded asbestos where there is much slippage as on high inertialoads. This material completely covers the inner surface of the drum 28.This has the advantage of providing more friction surface to wear than asmall piece of such friction surface mounted upon the weights. Itfurthermore permits the drum 38 to be made of materials which arereadily and cheaply produced such as plastic or die-castings otherwisenot suitable for friction surfaces.

In cooperation with inclined surface portions of web 29 (FIG. 2) thereis provided a correspondingly and oppositely tapered pulley element 39having a central hub 40 which is adjustably threaded or otherwisesecured upon drum hub 31 fixedly secured thereto as by set screw 41.

Thus there is shown in FIG. 1 one means for transmitting motion from thedriven member 12, namely the use of a pulley. It is understood that thepulley assembly 29-39 could be formed as a unit integral construction asa part of the drum assembly 12.

Other forms of coupling from the driven member are possible as forexample in the similar centrifugal clutch assembly shown in FIG. 4.

Here the driven member which includes drum 42 is a slightly differentshape from the drum 28 of FIG. 2 and includes a hub 43 whose exteriorsurface is irregularly shaped such as polygonal as at 44 (FIG.

or which could be splined so as to snugly receive thereover a similarlyshaped flexible coupling member such as shown at 45 for transmittingrotative motion. The shroud 46 of cylindrical form FIG. 4 extends arounda portion of the hub 43 and is adapted to snugly and cooperativelyreceive external cylindrical surface of the 4 length of the couplingmember (FIG. 5) so as to prevent slippage and to prevent distortion ofthe coupling member in operation and this also prevents slippage of acoupling member under sudden loads.

It is noted that the clutch weights 19 (FIG. 1) are not pivoteddiagonally opposite each other, as shown in FIG. 8, but are placedparallel to each other with the pivots on the same perpendicular axis.The other ends of weights 19 are therefore opposite each other on aperpendicular axis and can be restrained by only the single spring 23.

In referring to FIG. 1, it is noted that by changing the outer contourA-B of the weight 19 and shifting the area of contact to the area ofB-C, there will be a decrease in the self-energizing effect and renderthe clutch more suitable for higher inertia loads. On the other extreme,a centrifugal clutch with more self-energizing effect may be constructedas shown in FIG. 8, where the direction of rotation of the weights 19need be specified. In this case counterclockwise. With both weightsselfenergizing, the maximum amount of torque would be transmitted to thedriven member '12. The other extreme would be a centrifugal clutch suchas shown in FIG. 9 where there is one central post 61 for each weight 64in which the weights are constrained for radial movements only.

It is often desirable on centrifugal clutches to have a time delay onclosing after the clutch has obtained its maximum speed. This isparticularly desirable in order to obtain correct sequence of operationwhere the motor or other prime mover is coupled to two separate loadsand the second load should not be coupled until a short interval aftermaximum speed is attained. Such clutches have therefore been veryexpensive. FIG. 6 however illustrates a form of centrifugal clutch whichcan be adapted to delayed operation at small expense. Instead the singlespring 23 (FIG. 1) is removed and a single spring controlled dash-pot 47substituted. While it would operate with two dash-pots, the singledash-pot design makes it practical. Also note that with a singledash-pot controlling two weights, the movement is doubled in the pistonand the control less critical.

The latter consists of a cylinder 48 preferably of molded plastic withan attached semi-circular ring 49 on its closed end for attaching to thespring post 22 of the weight 19. Within this cylinder is a close fittingpiston 50 which has a number of small apertures 51 adjacent and aroundits periphery. These holes are covered on the top side (FIG. 6) by athin disc of spring metal to form the valve 52. The latter is held on byWasher 53 upon which rests compression spring 54. Tightly closing theend of the cylinder is a cap 55 which is permanently attached. Pistonrod 56 suitably fastened into the piston extends through cap 55 andterminates in the hook 57 adapted for connection with the correspondingpost 22 of the upper weight 19.

The piston rod is sealed by the flexible closure 58 which also has asnug fit over the outisde of cap 55. The entire cylinder is filled witha silicone fluid 59 of suitable viscosity to give the time delayrequired.

In operation as the disc 13 is rotated and approaches operating speed,the centrifugal force of the weights 19 overcomes the force of thespring 54, but before the weights can move outward, silicone fluid 59must pass by piston 50. This can be a slow process depending upon theviscosity of the fluid, and delays of considerable extent can be hadbefore contact of the weights with the friction lining 38 (FIG. 6).These delays are often useful. As the piston 50 and rod 56 move outward,the central boss of the elastometer seal 58 moves with it. However, thetotal volume inside the cylinder must remain constant, so the outer partof the seal moves down into the cylinder. Also, the piston, spring andfluid are heavier than the spring 23 (FIG. 1).

To compensate for this, drive disc 13 is provided with an aperture uponits opposite side into which the weight 71 is inserted and secured tocompensate and to maintain a balance. It is noted that on stopping thedelayed action clutch, the piston 50 can return rapidly to initialposition (FIG. 6) because the apertures 51 in the piston lets the fluidthrough freely merely raising the thin valve member 52 and thus a rapiddisengagement of the clutch results.

A modified centrifugal clutch is shown in FIG. 8 wherein mounted uponthe disc 13 are a pair of oppositely arranged weights 19. These weightsare pivotally mounted upon the diametrically arranged posts 18 whichproject from said disc.

The stop pillars or posts 24 which limit inward movemens of the weights19 to inoperative release position are the same construction as theposts 24 shown in FIG. 1.

The respective opposite ends of the weights 19 in this illustration havearcuate grooves 21 formed therein on the respective opposite sides ofadjacent weights providing the supporting posts 22 similar to what wasshown and described in FIG. 1 for receiving therebetween the respectivepair of tension springs 23. In this case instead of a single spring asin FIG. 1 there are provided a pair of such springs in view of thediametric pivotal mounting of the respective weights. In this case thecentrifugal clutch is self-energizing only if the weights are rotated ina counter clockwise direction.

A modified centrifugal clutch is shown in FIG. 9 wherein the drivemember includes a disc 60 from which projects a pair of diametricallyarranged parallel weight mounting and guiding posts 61 (FIGS. 9 andThese posts are aligned with the axis of the disc 60 and are providedwith outwardly extending inwardly converging surfaces 62 to thus form awedge shape.

The posts 61 at their outer most portions have an overhanging lip 63adapted to supportably and retainingly receive corresponding portions ofthe respective weights 64 restraining their movements to radialmovements with respect to the disc 60, within the confines of drum 28.

The respective weights 64 have a similarily shaped aperture 65therethrough which is adapted to cooperatively receive the wedge shapedpost 61. The said aperture 65 is enlarged inwardly as at 66 by which therespective weights 64 are capable of radial outward movements when theweights have been rotated at a sufficient speed.

The respective end portions of the weights are grooved as at 67throughout a portion substantially midway of their width to define theoppositely aranged posts 68 between an adjacent pair of weights 64 atthe respective opposite ends to provide a means of receiving the loopedends of the tension springs 69 to maintain the assembled relation of theparts shown and wherein such construction there is a tendancy for thesprings to remain in the assembled relationship against accidentaldisengagement from the weights since the corresponding loops at theopposite ends of the springs extend to opposite sides of the respectiveweights at their adjacent ends.

The lips 63 prevent linear movement of the weights 64. When this clutchapproaches its operating speeds, the weights 64 begin to move outwardlyuntil they contact the friction liner 38 of the drum 28, whereupon theyare forced against the angular surface 62 of the posts which furtherurges them outward. The amount of self-energization can be controlled bythe angle of the inclined surface at 62. Centrifugal clutches of thistype can be constructed with three, four or more such weights 64 and acorresponding number of springs so that the weights form an all butcontinuous surface in contact with the friction material 38 inoperation.

In the present disclosure the weights here and above described namelyweights 19 or 64 may be formed of powdered metal or die-cast withoutsubsequent machining. Thus the entire construction lends itself to highspeed economical low cost fabrication.

Low inertial loads can be started with the completely self-energizingclutch such as shown in FIG. 8, moderate 6 inertial loads with the dualrotation centrifugal clutch as shown in FIG. 1, and high inertial loadswith a variation of the design shown in FIG. 9.

If desired, the clutches may include compression springs and provide afixed mechanism torque in one direction, though due to a differentself-energizing effect, a possibly different value torque in theopposite direction. Except for the springs, the construction isidentical.

In FIG. 9 for instance, compression springs may be substituted fortension springs. There would be two short pillars cast on the weights ateach end to locate the springs and to prevent movement in one direction.The slope 62 could be dilferent on opposite sides to change theselfenergizing effect, and therefore, the torque when reached.

Such clutches are widely used in washing machines, and the presentconstruction would be particularly economical.

While there is shown in FIG. 2 driven member 12 journalled to drivemember 11, it does not need to be. They could be mounted on separateshafts on the same axis adjacent to each other, say a motor shaft and apump shaft, yet still retain all the features above defined.

Having described my invention, reference should now be had to thefollowing claims.

I claim:

1. In a centrifugal clutch, a drive member including an apertured discand a hub adapted to receive a drive means;

a pair of parallel spaced diametrically opposed posts on one side of andprojecting from the disc and aligned with the disc axis;

a pair of diametrically and oppositely arranged weights at their centralportions having apertures therethrough, movably and guidably mounted onsaid posts respectively;

their outer working edges being arcuate;

a radially and outwardly extending lip on each post overlying, guidablyreceiving and retainingly engaging said weights, limiting them to radialmovements;

said posts being wedge-shaped in cross-section converging towards theirradial outward edges;

the apertures extending through each weight being similarly shaped, butenlarged to permit radial outward movements, said weight aperturesdefining outwardly converging surfaces guidably bearing against saidposts;

coiled springs interconnecting corresponding opposite ends of saidweights, with the latter normally retained by said posts in radiallyinward release position;

and a driven member including an apertured drum loosely surrounding andradially spaced from said disc and weights and having a hub journalledupon said disc hub;

means to prevent relative endwise motion of said hubs;

coupling means on said drum hub;

and a sleeve of friction material secured upon the interior of said drumnormally spaced from said weights.

2. In the centrifugal clutch of claim 1, the free ends of said weightsbeing arcuately cut away and arranged to define oppositely extendingspring retaining posts.

3. In the clutch of claim 1, said drum including a radial web, the meansto prevent endwise relative movement of the hubs including an annularrecess in the disc hub cooperatively receiving one end of the drum hub;

said one end of the drum hub extending axially into said drum;

and a washer secured upon the other end of said disc hub looselyengaging said drum hub at its other end.

4. In clutch of claim 1, said drum including a radial web joining thedrum hub;

the outer surface of the drum hub being irregularly shaped to receivethe similarly shaped inner surface of a coupling element, and an annularshroud projecting from said web overlying said drum hub, adapted 7 toretainingly receive the outer surface of said cou- 2,868,343 1/1959Sproul 192-105B1 pling element. 3,224,541 12/1965 Yarnarnoto 192-105C-1References Cited UNITED STATES PATENTS 2,703,163 3/1955 Millar192--105B-1 5 U.S.C1.X.R.

2,718,294 9/1955 Armstrong 192105B-1 19254, 55, 109 2,851,893 9/1958Putz 192-105B-1 BENJAMIN W. WYCHE, Primary Examiner

